铸铁件凝固后的控制冷却工艺

Controlled Cooling Process of Iron Castings after Solidification

由于只借助于加入合金元素和控制化学成分来获得铸铁最终组织具有局限性,提出了控制冷却工艺,并以日本洋马公司生产的大型柴油机缸体为例进行了介绍,生产结果显示:(1)铸件凝固后的平均冷却速率从原来的5.7℃/h提高到16℃/h;(2)铸件冷却到500℃所需的时间,由原来的46 h缩短到18 h;(3)铸态铸件各部位残留应力测定值的平均值有所降低;(4)铸态铸件各部位本体强度的平均值大约提高15 MPa;(5)基体组织中铁素体的体积分数减少。同时,还介绍了美国铸造协会与Missouri科技大学合作,用控制冷却工艺替代等温淬火工艺的研究工作。

Because of the limitation of obtaining the final microstructure of cast iron only by adding alloy elements and controlling chemical composition,the controlled cooling process was put forward and an introduction was conducted by taking the heavy diesel engine block produced by Japan Yangma Company as an example.The production result showed:(1)The average cooling rate of casting after solidification raised from original 5.7℃/h to 16℃/h.(2)The time of the casting cooling to 500℃reduced from original 46 h to 18 h.(3)The average residual stress measurement value on various locations of the as-cast casting had reduction.(4)The average strength value of various locations of the as-cast casting increased by about 15 MPa.(5)The ferrite volume fraction in matrix structure reduced.In addition,an introduction was given to the research of using controlled cooling to replace isothermal quenching process conducted by cooperation of AFS with Missouri Technology University.